fix(getmessages): ZMS-260: messages.js getMessages allow unseen request flag to be false (#861)

* messages.js allow unseen request flag to be false to allow search for seen messages only

* messages.js check filterUnseen type instead of just checking for undefined

Author: NickOvt

lib/api/messages.js

@@ -321,7 +321,9 @@ module.exports = (db, server, messageHandler, userHandler, storageHandler, setti
                     mailbox: Joi.string().hex().lowercase().length(24).required().description('ID of the Mailbox')
                 },
                 queryParams: {
-                    unseen: booleanSchema.description('If true, then returns only unseen messages'),
+                    unseen: booleanSchema.description(
+                        'If true, then returns only unseen messages. If false, then returs only seen messages. Leave blank to return all messages'
+                    ),
                     metaData: booleanSchema.default(false).description('If true, then includes metaData in the response'),
                     threadCounters: booleanSchema
                         .default(false)
@@ -472,7 +474,7 @@ module.exports = (db, server, messageHandler, userHandler, storageHandler, setti
             let pageNext = result.value.next;
             let pagePrevious = result.value.previous;
             let sortAscending = result.value.order === 'asc';
-            let filterUnseen = result.value.unseen;
+            const filterUnseen = result.value.unseen;
 
             let includeHeaders = result.value.includeHeaders ? result.value.includeHeaders.split(',') : false;
 
@@ -511,8 +513,8 @@ module.exports = (db, server, messageHandler, userHandler, storageHandler, setti
                 mailbox
             };
 
-            if (filterUnseen) {
-                filter.unseen = true;
+            if (typeof filterUnseen === 'boolean') {
+                filter.unseen = filterUnseen;
             }
 
             let total = await getFilteredMessageCount(filter);